Remove weird session fallback in /api/user/
Remove weird session fallback in /api/user/

It was never used, and the idea of using the session user if there is
any error with the oauth token (missing, invalid, whatever) is extremely
obscure and prone to errors.

ThiefMaster/indico,ThiefMaster/indico,ThiefMaster/indico,DirkHoffmann/indico,indico/indico,ThiefMaster/indico,pferreir/indico,DirkHoffmann/indico,DirkHoffmann/indico,pferreir/indico,indico/indico,pferreir/indico,DirkHoffmann/indico,indico/indico,pferreir/indico,indico/indico